Extravasation in the knee induced by antidromic stimulation of articular C fibre afferents of the anaesthetized cat.

Abstract

Electrical stimulation of the cut distal end of the posterior articular nerve (p.a.n.) of the cat knee joint resulted in significant extravasation of plasma proteins and erythrocytes into the synovial cavity of the knee. This effect was mediated by group IV afferents (C fibres) since stimulation of p.a.n. suprathreshold for group II or III afferents but subthreshold for group IV afferents did not produce extravasation. Unmyelinated sympathetic efferent fibres in the joint nerve did not contribute to the extravasation and were responsible for a diminution of this response as shown by the enhanced extravasation occurring after adrenergic blockade. Plasma and erythrocyte extravasation was mediated by afferents containing substance P (SP), as demonstrated by the reversible abolition of extravasation when the substance P antagonist (D‐Pro4,D‐Trp7,9,10)‐SP (4‐11) was injected into the synovial cavity. In some animals it was observed that electrical stimulation of the cut distal end of p.a.n. in one limb resulted in extravasation in the contralateral knee joint. It is suggested that articular C fibre afferents could make a significant neurogenic contribution to the initiation or maintenance of inflammatory joint disease.

Regeneration of Unmyelinated Axons After Injury of Mammalian Peripheral Nerve

“…Inflammation of a joint causes a general increase in receptor sensitivity (Guilbaud et al 1985;Schaible & Schmidt, 1985) and it may be that the 'silent' receptors are recruited under these circumstances. Some of these afferents are capable of eliciting vasodilatation and plasma extravasation upon antidromic stimulation (Ferrell & Russell, 1986;Ferrell & Cant, 1987) The question of whether or not peripheral neurones die after injury is not new but it is central to the matter of how well tissues become reinnervated by afferent and efferent unmyelinated axons after injury. From the experimental studies carried out to date the general consensus of opinion is that there is a loss; now the questions are how extensive is it and are all the types of neurone found in peripheral nerves affected equally?…”

The role of glutamate and GABA receptors in the generation of dorsal root reflexes by acute arthritis in the anaesthetized rat.

“…However, preliminary data from dorsal root filament recordings in acutely arthritic cats indicate that some of the activity is conveyed in primary afferent C fibres (Sluka, Rees, Westlund & Willis, 1994c). Antidromic impulses, evoked by electrical stimulation of cutaneous nerves, can cause peripheral vasodilation and increase the permeability of the vasculature in the region of the peripheral nerve terminals (see references in Ferrell & Russell, 1986). The present results extend these observations, demonstrating that, following initiation of arthritis, antidromic activity in articular nerves may be evoked by mechanical stimuli.…”

Properties of Sensory Neurons Innervating Synovial Joints

“…The lumps are thought to be individual receptive sites. Most c fiber terminals contain vesicles of substance P and calcitonin-gene related peptide (CGRP), peptides that are released on activation [Ferrell and Russell, 1986] and are involved in inflammatory responses.…”